Device for driving movable machine parts in reverse direction

ABSTRACT

Device for driving movable machine parts, particularly in dobbies, in reverse directions. The device has at least one double-acting piston driving unit and at least one double-acting piston driven unit, said units being mutually interconnected by a by-passing circuit in which a mechanism for controlling said bypassing circuit is interposed. In the disclosed embodiment, the by-passing circuit has at least two separate branches, each of which connects one point at the extreme dead center of the piston of the driving unit with two points at both termini of travel of the double-acting driven piston unit, a distribution sliding valve and a channel closed thereby being mounted within the area of branching of said branches of the by-passing circuit, said channel interconnecting said branches of the by-passing circuit.

United States Patent [191 Dostal [451 Feb. 4, 1975 DEVICE FOR DRIVING MOVABLE MACHINE PARTS IN REVERSE DIRECTION [21] Appl. No.: 325,769

[30] Foreign Application Priority Data 518,109 3/1955 Italy 139/55 1,296,090 5/1962 France 139/55 1,224,357 2/1960 France 139/317 Primary ExaminerJames Kee Chi [57] ABSTRACT Device for driving movable machine parts, particularly in dobbies, in reverse directions. The device has at least one double-acting piston driving unit and at least one double-acting piston driven unit, said units being mutually interconnected by a by-passing circuit in which a mechanism for controlling said by-passing circuit is interposed. 1n the disclosed embodiment, the by-passing circuit has at least two separate branches, each of which connects one point at the extreme dead center of the piston of the driving unit with two points at both termini of travel of the double-acting driven piston unit, a distribution sliding valve and a channel closed thereby being mounted within the area of branching of said branches of the by-passing circuit, said channel interconnecting said branches of the bypassing circuit.

4 Claims, 6 Drawing Figures PATENTEDFEB 41975 3.863.681 smzannrr? llllllll H PATENTED H975 3.863.681

- SHEET 30F 3 9 mm |lllllllllllllllIllllllllllllllllllllllllllllll \Illl l l lllllllllll DEVICE FOR DRIVING-MOVABLE MACHINE PARTS IN REVERSE DIRECTION The present invention relates to a device for movable machine parts, particularly in dobbies. in reverse direction.

In textile machines, particularly in weaving machines, mechanisms performing linear reverse motions are used. A typical mechanism of such type is e.g. the mechanism for driving heald shafts in a weaving machine. For exerting a linear reverse motion of heald shafts, various systems are used, as for example a system of rotating cams or swinging levers, the motion of which is derived from a crank mechanism, etc. Upon weaving various weaves in fabrics, it is necessary to control the movement of the separate heald shafts according to a predetermined program. For that purpose various embodiments of dobbies are used. The drive of the separate dobby units in dobbies is usally mechanical, electromagnetic, pneumatic, or hydraulic, the latter two being used with open circuits.

The disadvantages of all those systems consists in their very considerable dimensions, which are dictated by the type of drive and control employed, and in the considerable noise which they generate, such noise increasing with increasing velocity up to an unbearable volume. The traverse of the separate heald shafts is also inaccurate, particularly in dobbies in which a drive with an open pneumatic or hydraulic circuit is used. The dobbies hitherto known have a reduced maximum limit of rotational speed because of their complicated mechanisms. The velocity of rotation of their shafts is also limited by the limit in precision of manufacture of the separate parts of the dobby necessitated by the small mounting space available with respect to the specific conditions in a weaving machine. The dobbies consist of a large quantity of parts engaged with each other or mutually rotatably interconnected. Under such conditions, it is very difficult to secure reliable lubrication of the parts and consequently said parts soon undergo wear and have short service lives. The long chains of driving and control members of a dobby mechanism are sources of considerable inaccuracies in the operation of the mechanism.

The majority of dobbies hitherto known also require a large floor space. The large dimensions of dobbies either considerably increase the floor space of the weaving machine, or require a strong auxiliary construction for their mounting in an overhead arrangement; the direct mounting of dobbies on the weaving machine is entirely out of question.

A number of dobbies use power accumulated by various types of springs for the active retraction of heald shafts. These systems of driving operate intermittently; during the traverse of a heald shaft it is necessary for example to use double the power which is required for its retraction. Considerable vibration, therefore, results which makes the correct operation of a dobby practically impossible at higher rotation speeds.

The dobby must be also equipped with a device for prcselecting the lifting of heald shafts. The signal is usually transmitted to the driving mechanisms of the dobby by mechanical tranmissions. The transmissions are usually connected with the driving mechanisms so as to require considerable floor space, and therefore the pulse or signalling mechanism is directly bound to the dobby.

The present invention has among its objects the removing or mitigation of the above-mentioned disadvantages of the hitherto known dobbies. The invention provides a dobby with smaller space requirements than those of previous dobbies. The dobby of the invention has at least one driving and one driven double-acting piston unit, the two units being mutually interconnected by a by-passing circuit having mechanism for controlling said by-passing circuit.

Further advantages and features ofthe present invention are set forth in the following description of an illustrative, non-limiting embodiment of the invention and will be apparent from the accompanying drawings, in which FIG. I is a view in section through the program control mechanism and the heald shaft, the view showing a part of the heald;

FIG. 2 is a fragmentary view in section through the body of the control mechanism, the distribution slide valve being shown in a central position;

FIG. 3 is a view similar to FIG. 2, but with the distribution slide valve being shown in its extreme right position:

FIG. 4 is a view similar to FIGS. 2 and 3 but with the distribution slide valve being shown in its extreme left position;

FIG. 5 is a view in front elevation of the dobby according to the present invention; and

FIG. 6 is a plan view of the dobby, the dobby being shown in association with the driving part.

In the following specification there is described one dobby unit according to the present invention. It is to be understood that all remaining units,of which a plurality are mounted on the weaving machine, are identical. The number of dobbies employed corresponds to the number of heald shafts in the harness of the weaving machine.

The program control mechanism of the invention has a body 1. A driving double-acting piston unit 2 is mounted in the upper part of body 1, a piston 3, which is connected by means of a piston rod 4 and a sliding block 5 to the connecting rod 6 of eccentric 7, being mounted on a driving shaft 8. Shaft 8 is drivingly connected to e.g. the main shaft 10 of the weaving machine by means of a gear mechanism 9. i

In the lower part of the body 1, there is mounted a double-acting driven piston unit 11. Piston 12 of unit 11 is articulated by means of a piston rod 13 to a twoarm lever 14 pivoted on a fixed fulcrum and a crank tie rod 15. A tie rod 16 is attached to the upper arm of lever 14, rod 16 being pivotally attached to a heald shaft 17. The shaft 17 is a part of a heald frame having elements 18 for controlling the position of warp threads not shown. As shown in FIG. 5, the crank tie rod 15 constitutes a link which extends to the opposite side of the same heald shaft 17. The right hand end of link 15 being pivotally connected with one arm of a two-arm lever 14' and a tie rod 16' for lifting heald shaft 17, the one arm of tie rods 16 and 16' moving in unison.

A distributing slide valve 19 is slidable in a bore in the central part of body I, the-valve 19 being constituted by a pair of pistons 20, 21, which are mutually interconnected by a slide valve rod 22. The ends of slide valve rod 22 are provided with guides 23 and 24, guide 24 having an impulse mechanism 26 attached thereto by means of a spring-loaded lever 25. The impulse mechanism consists of an intermittently rotating drum 27 affixed to a shaft 31 and a control chain 28. Drum 27 is driven from driving wheel 29 on driving shaft 8 (FIG. and further by transmission to a gear 30, which is mounted on said shaft 31.

Control chain 28 carries a plurality of projections 32 arranged in sets of three different heights, said height of the projections 32 determining the position of distribution slide valve 19 into one of three possible positions (FIGS. 2, 3, and 4). The distribution of the projections 32 on the control chain 28 is arranged according to a required weave pattern of the fabric to be manufactured.

In the uppermost part of the body 1 there is formed a central chamber 33, chamber 33 being common to all bodies 1, which are arranged in a row behind the particular body 1 here shown. The central chamber 33 provides a storage sump or tank for the operating fluid, in the given case a hydraulic fluid such as oil. The central chamber 33 has two mutually separated subchambers 34 and 35 for operating fluid, said sub-chambers being interconnected with said central chamber 33 by means of at least one suction valve 36 and one pressure relief valve 37.

The double-acting driving piston unit 2 is interconnected in both dead center positions of its piston 3 by channels 38 and 39 with the operating fluid subchambers 34 and 35.

The double-acting driving piston unit 2 is further connected by means of a by-passing circuit with the double-acting driven piston unit 11, said by-passing circuit being substantially constituted of two separate branches 40 and 41 in the form of channels. The abovementioned distribution slide valve 19 at those points at which branches 40 and 41 are divided into branches 40a, 40b and 41a, 41b. Branches 40 and 41 of the bypassing circuit are connected to the double-acting driving piston unit 2 at the points of both extreme dead centers of their piston 3, and at the point of mounting the by-passing slide valve 19 each is provided with a pair of parallel by-passing channels 42a, 42b and 43a, 43b. In the center of the said pairs of parallel by-passing channels 42a, 42b and 43a, 43b, there are provided bypassing channels 44 and 45 of branches 41a and 40a, which mutually converge and which are connected to the driven double-acting piston unit 11 at the point of one terminus of travel of its piston 12.

At both sides of the two pairs of parallel by-passing channels 42a, 42b and 43a, 43b there are further bypassing channels 46 and 47 of branches 40b and 41b, which also mutually converge and which are connected to the double-acting driven piston unit 11 at the point of the second terminus of travel of its piston 12.

The said by-passing channel 47, 43a, 44 and 43b, likewise as channels 42a, 45, 42b and 46 are arranged into two groups and are arranged in the axial direction according to the distribution slide valve 19 e.g. at regular distances, the length of each of pistons or 21 of the distribution slide valve 19 being such that piston 20 or 21 in one of the mentioned three positions of distribution slide valve 19 covering always at least two mutually neighboring channels in each group thereof.

The free space around the slide valve rod 22 between the two pistons 20 and 21 constitutes a channel 48 which, as will be explained further, in the central position of distribution slide valve 19 interconnects both branches 40 and 41 of the by-passing circuit.

The unit of the dobby according to the present invention operates as follows:

Presuming that all channels, as well as spaces in both the driving and driven double-acting piston units 2 and 11, are filled up with the operating fluid, then in the central position of distribution slide valve 19 (FIG. 2), the operating fluid is passed, upon reverse motion of piston 3 of the double-acting driving piston unit 2, through branches 40 and 41 and channel 48 around the slide valve rod 22 alternatingly from the space in front of the said piston 3 into the space thcrebehind, and

vice-vcrsa.

This operation phase of the dobby can be called the idle run, as piston 12 of the double-acting driven piston unit 11 remains at rest in one of its extreme positions. The appurtenant heald shaft 17 remains likewise at rest.

When the control chain 28 is moved in such manner that a projection 32 of minimum height or a point without any projection 32 moves to a position opposite to the spring-loaded lever 15, the distribution slide valve 19 is traversed into its extreme right position (FIG. 3), whereupon the channel 48 around slide valve rod 22 is closed, and simultaneously the double-acting driving piston unit 2 and the double-acting driven piston unit 11 are interconnected by means of branches 41 and 41b and 40, 40a. When piston 3 of the driving piston unit 2 moves from right to left, the operating fluid is forced in front thereof through branch 41 into bypassing channels 43a, 47 and the branch 41b connected thereto. The said operating fluid begins to act upon piston 12 by penetrating the double-acting driven piston unit 11 and traverses said piston from left to right. The operating fluid, which is situated in front of the piston 12, is forced back into the double-acting driving piston unit 2 through branch 40a, by-passing channels 45, 42b, and branch 40.

By reverse motion of piston 3 of the double-acting driving piston unit 2, an opposite reverse motion of piston 12 of the double-acting driven piston unit 11 takes place and simultaneously there is produced a reverse motion of heald shaft 17. By traversing distribution slide valve 19 into its extreme left terminal position upon one of projections 32 on the control chain 28 pressing upon lever 25, the mutually opposite motion of piston 3 of the double-acting driving piston unit 2 and the piston 12 of the double-acting driven piston unit 11 is changed to a parallel motion. Branch 41a is connected with branch 41 by means of by-passing channels 43b, 44, said branch 41a being a continuation of branch 40a, and branch 40b being a continuation of branch 41b. Branch 41a is connected by means of bypassing channels 42b, 48 with branch 40.

The described mechanism makes possible the reverse motion of the weaving machine for the purpose of detecting a badly inserted weft, or for other weaving purposes.

The above-described dobby unit according to the present invention can be completed with identical units, which are arranged in a row behind the particularly described unit, said units being arranged in the form of a mirror image at the opposite side of the driving shaft 8, being shifted ahead or back for one-half of their thickness. This makes it possible to considerably reduce the spacing between the separate units and thus to reduce the required floor space.

The driven, or respectively driving, double-acting piston units 11 or 2, respectively, can be made as separate units in separate housings thus making possible constructional modifications of the dobby according to the present invention for use with a number of various known types of weaving machines.

The detailed specification as given above is given only for understanding the present invention. as certain further modifications thereof will be obvious to those skilled in the art upon viewing the appended claims.

What is claimed is:

l. A device for driving healds of weaving machines in reverse directions, comprising at least one doubleacting driving piston unit and at least one double-acting driven piston unit, a by-passing circuit mutually interconnecting the two units, and a mechanism for controlling said by-passing circuit, the by-passing circuit comprising at least two separate branches of which each connects one point at one terminus of travel of the piston of the driving unit with two points at the termini of travel of the piston of the double-acting driven piston unit, a distribution sliding valve and a channel closed thereby mounted within the area of branching of the branches of said circuit, said channel mutually interconnecting both of said branches of the by-passing circuit, the branches of the by-passing circuit which are connected to the termini of the travel of the piston of the driving unit being provided at the points of mounting the distribution slide valve with pairs of parallel bypassing channels, in the center of each pair of said parallel by-passing channels there being by-passing channels of one branch of the by-passing circuit connected to one point at one terminus of travel of the piston of the driven piston unit, both sides of the said parallel bypassing channels of the other branch of the by-passing circuit being connected to the point at the other terminus of travel of the piston of the driven piston unit.

2. A device as claimed in claim 1 wherein the points at both termini of travel of the piston of the doubleacting driving unit are permanently interconnected with mutually separated chambers storing operating fluid, said chambers being provided with both suction and pressure relief valves.

3. A device as claimed in claim 1, wherein both the driving and driven double-acting piston units together with the mechanism for controlling the by-passing circuit are disposed in one housing.

4. A device as claimed in claim 3, comprising a plurality of housings arranged in one row behind each other, the double-acting driving piston units being attached to and driven by a common driving unit. 

1. A device for driving healds of weaving machines in reverse directions, comprising at least one double-acting driving piston unit and at least one double-acting driven piston unit, a bypassing circuit mutually interconnecting the two units, and a mechanism for controlling said by-passing circuit, tHe by-passing circuit comprising at least two separate branches of which each connects one point at one terminus of travel of the piston of the driving unit with two points at the termini of travel of the piston of the double-acting driven piston unit, a distribution sliding valve and a channel closed thereby mounted within the area of branching of the branches of said circuit, said channel mutually interconnecting both of said branches of the by-passing circuit, the branches of the by-passing circuit which are connected to the termini of the travel of the piston of the driving unit being provided at the points of mounting the distribution slide valve with pairs of parallel by-passing channels, in the center of each pair of said parallel by-passing channels there being by-passing channels of one branch of the bypassing circuit connected to one point at one terminus of travel of the piston of the driven piston unit, both sides of the said parallel by-passing channels of the other branch of the bypassing circuit being connected to the point at the other terminus of travel of the piston of the driven piston unit.
 2. A device as claimed in claim 1 wherein the points at both termini of travel of the piston of the double-acting driving unit are permanently interconnected with mutually separated chambers storing operating fluid, said chambers being provided with both suction and pressure relief valves.
 3. A device as claimed in claim 1, wherein both the driving and driven double-acting piston units together with the mechanism for controlling the by-passing circuit are disposed in one housing.
 4. A device as claimed in claim 3, comprising a plurality of housings arranged in one row behind each other, the double-acting driving piston units being attached to and driven by a common driving unit. 